This article was published in Digital Applications in Archaeology and Cultural Heritage in 2018, and the preprint is available for download on SocArXiv. The gahagan-analysis file contains the data (landmarks and semilandmarks) and R scripts used in the analysis. The unprocessed data have been uploaded to the Open Science Framework, and the processed meshes to Zenodo @ CERN. Those data are embargoed for a period of five years, as the analysis of these bifaces is ongoing.